Print hammer actuating mechanism

ABSTRACT

A printer with a hammer actuating mechanism comprising elongated drive-ratchet and control-cam shafts mounted in spaced parallel relationship and a plurality of pivotal hammers extending transversely of the shafts. A drive pawl pivotally mounted on each hammer arm is engageable by the drive-ratchet shaft for pivotal actuation of the hammer for producing a printout and the control-cam shaft is rotatable for releasing the drive pawls for engagement by the drive-ratchet shaft. A pivotal control arm is operable by an electromagnet for actuation by the drive-ratchet shaft in the manner of the hammer actuation to rotate the control-cam shaft for releasing the drive pawls.

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States P2126111 91 [451 Jan. 16, 1973 Voegelin [54] PRINT HAMMERACTUATING MECHANISM [75] inventor: Howard H. Voegelin, Cheshire,

- Conn.

[73] Assignee: Veeder Industries Inc., Hartford,

Conn.

[22] Filed: Sept. 3, 1970 [21] Appl. No.: 69,304

[52] U.S. Cl. ..10l/93 C [51] Int. Cl ..B4lj 9/28, B41j 9/3 8. [58]Field of Search .101/93 C, 93 R, 96, 91

[56] I References Cited UNlTED STATES PATENTS 3,018,721 1/1962Monticello et al 101/93 C 3,175,487 A 3/1965 Braden et al ..101 93 c3,286,625

11/1966 Petit ..1()1/93 C 11/1967 Poland ......l0l/93C 6/1971 .laensch..l0l/93C Primary Examiner-William B. Penn Attorney-Prutzman, Hayes,Kalb & Chilton 57 ABSTRACT A printer with a hammer actuating mechanismcomprising elongated drive-ratchet and control-cam shafts mounted inspaced parallel relationship and a plurality of pivotal hammersextending transversely of the shafts. A drive pawl pivotally mounted oneach hammer arm is engageable by the drive-ratchet shaft for pivotalactuation of the hammer for producing a printout and the control-camshaft is rotatable for releasing the drive pawls for engagement by thedriveratchet shaft. A pivotal control arm is operable by anelectromagnet for actuation by the drive-ratchet shaft in the manner ofthe hammer actuation to rotate the control-cam shaft for releasing thedrive pawls.

10 Claims, Drawing Figures INVENTOR HOWARD J. VOEGELIN ATTORNEYSPATENTEDJAH 16 I975 SHEET 2 I]? 2 BRIEF SUMMARY OF THE INVENTION Thepresent invention relates generally to printers of the type having oneor more print hammers for producing a printout and more particularly toa print hammer actuating mechanism having a drive shaft providing powerfor actuating the hammers.

It is a principal aim of the present invention to provide a new andimproved print hammer actuating mechanism for individually connecting aplurality of print hammers for actuation by a common drive shaft.

It is another aim of the present invention to provide a new and improvedelectromagnetically operated print hammer actuating mechanism whichprovides a single printout for each energization of its electromagneticoperator.

It is another aim of the present invention to provide a new and improvedprint hammer actuating mechanism which permits employing any desirednumber of hammers.

It is a further aim of the present invention to provide a new andimproved print hammer actuating mechanism which provides reliableoperation over a long service-free life.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

A better understanding of the invention will be obtained from thefollowing detailed description and the accompanying drawing of anillustrative application of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side elevation view, partly broken away and partly insection, of a printer incorporating an embodiment of a print hammeractuating mechanism of the present invention.

FIG. 2 is a top plan view, partly broken away and partly in section, ofthe print hammer actuating mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing indetail, a printer l incorporating an embodiment of a print hammeractuating mechanism of the present invention comprises an elongateddrive-ratchet shaft 12 which is continuously rotated (e.g., at 1,200RPM) by a suitable electric motor (not shown), an elongated cam orhammer control shaft 14 (mounted with the drive-ratchet shaft 12 inlaterally spaced parallel relationship), and a plurality of separateprint hammer mechanism (only one of which being shown in the Figure)mounted in aligned or stacked relationship for cooperation with theshafts l2, 14.

Each hammer mechanism 20 comprises a generally L-shaped hammer 22pivotally mounted on a support shaft 24 and having an enlarged head 26.The hammer 22 is operable for performing a printout by pivoting thehammer 22, in the clockwise direction as viewed in the Figure, intoengagement with a strip of paper 28 lying adjacent the type character 30of a print wheel 32. The print hammer normally rests in its withdrawnpivotal position shown in full lines in the Figure in engagement 44 thatthe pawl 40 re-engages and is pivoted by the with a support plate 34. Ahammer drive pawl 40 pivotally mounted on the hammer 22 has a firsthooked' end 42 having a shoulder 43 engageable by a drive shoulder 44 ofthe drive-ratchet shaft 12 and a second tail end 46 engageable with thecam shaft 14. A tension spring 48 connected to the tail end'46 of thehammer drive pawl 40 provides for biasing the pawl 40 into engagementwith the drive-ratchet shaft 12 and for biasing the hammer 22 to itswithdrawn'pivotal position shown in full lines in the Figure. 1

A tension spring 50 is connected to the cam shaft 14 for holding the camshaft 14 in its normal angular position shown in the Figure where itsouter cylindrical cam edge 52 is engageable with the hammer drive pawls40 to hold or latch them out of engagement with the driveratchet shaft12. The hammer control cam 14 when rotated approximately 25 against thebias of the return spring 50, in the clockwise direction as viewed inthe Figure, substantially simultaneously .unlatches or releases thehammer drive pawls 40 for engagement with the drive-ratchet shaft 12,whereupon the drive shoulder 44 of the shaft 12 engages the pawlshoulders 43 to pivot the hammers 22 upwardly against the bias of theirreturn springs 48 to produce a printout. The drive shoulder 44preferably extends axially along a curved generally helical path suchthat the hammer drive pawls 40 are engaged in succession rather than allat once to reduce the required drive torque forthe shaft 12 and toreduce the shock on the mechanism.

' The helical shoulder 44 extends through an angle of approximately 90and each hammer drive pawl 40 is driven by the drive-ratchet shaft 12during approximately 60 of rotation of the shaft 12 such that the entireprinting operation is performed during approximately 150 of rotation ofthe shaft 12.

The drive shoulder 44 and drive pawl shoulders 43 are contoured suchthat each pawl shoulder 43 becomes disengaged from the drive shoulder 44just prior to the engagement of the hammer 22 with the. paper 28 and theprinting is'performed by the inertia of the moving hammer. Also, therebound of each hammer occurs sufficiently quickly after thedisengagement of the pawl shoulder 43 from the'drive shoulder cam shaft14 out of engagement with the drive-ratchet shaft 12 before the driveshoulder 44 can complete a revolution to re-engage the pawl shoulder 43.During such return movement of the hammer 22 the drive pawl 40 initiallyrides over the outer cylindrical surface 60 of the drive-ratchet shaft12 which thereby pivots the pawl for re-engagement with the cylindricalcam edge 52 of the cam shaft 14 whereupon the cam edge 52 ratchet shaft12. Also, the hammer actuation is such that all of the hammer drivepawls 40 are out of engagementwith the cam shaft 14 at the same time topermit the cam shaft 14 to be rotated back to its normal latchingposition by the return spring 50 before the pawls 40 return to re-engagethe cam shaft 14.

A pivotal actuator mounted on the support shaft 24 has a curved tail endengageable with a pin 72 on the cam shaft 14 for rotating the cam shaftfor releasing the drive pawls. An actuator drive pawl 76 identical tothe hammer drive pawls 40 is pivotally mounted on the pivotal actuator70 for engagement with the driveratchet shaft 12 (in the manner of thehammer drive pawls 40) for pivoting the actuator 70 sufficiently torelease the drive pawls. A control cam 80 mounted coaxially with the camshaft 14 provides for selectively holding the actuator drive pawl 76 outof engagement with the drive-ratchet shaft 12 in the manner of the camshaft 14, and a tension spring 82 biases the control cam 80 to itsnormal angular position where its cylindrical surface 84 engages theactuator drive pawl 76 to hold it out of engagement with thedrive-ratchet shaft 12.

The control cam 80 is adapted to be rotated against the bias of thespring 82 to release the actuator drive pawl 76 by an electromagnet 85having an armature 86 with a hooked end engageable with a pin 88 on thecontrol cam 80. The armature 86 is biased to its withdrawn position inengagement with a guide or stop 90 by a tension spring 92. Theelectromagnet 85, when energized, withdraws the armature 86 to pivot thepin 88 and control cam 80 for releasing the actuator drive pawl 76 andthen releases the pin 88 to permit the control cam 80 to return to itsnormal position. Upon de-energization of the electromagnet 85, thearmature 86 rides over the pin 88 to position the armature forre-engaging the pin 88 when the electromagnet is re-energized. Thus, byeither momentarily energizing the electromagnet 85 or holding itenergized, the control cam 80 will be rotated and released to permit theactuator drive pawl 76 to momentarily rotate and release the cam shaft14. Such ensures that the hammer drive pawls 40 are permitted to engagethe drive ratchet shaft 12 for actuating the print hammers 22 only oncefor each operation of the electromagnet 85. Also, the actuator drivepawl 76 is operated by the drive-ratchet shaft 12 to timely release thehammer drive pawls 40 for initial engagement with the outer cylindricalsurface 60 of the drive-ratchet shaft 12 thereby ensuring that thehammer drive pawls 40 are readied for proper engagement by the driveshoulder 44 for proper actuation of the print hammers 22.

As will be apparent to persons skilled in the art, variousmodifications, adaptations and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

1 claim:

1. A print hammer mechanism comprising an elongated rotatabledrive-ratchet shaft adapted to be continuously rotated during operationand having integral axially extending drive shoulder means, a pluralityof axially spaced hammers extending transversely of the drive-ratchetshaft and pivotally mounted about an axis generally parallel to thedrive-ratchet shaft axis to be pivotally actuated for producing aprintout, a hammer drive pawl having an operating shoulder pivotallymounted on each hammer about an axis spaced from and generally parallelto the pivotal axis of the hammer, each drive pawl being mounted toextend from its pivotal axis transversely of the drive-ratchet shaft tobe pivoted to bring its operating shoulder into engagement with thedrive shoulder means of the drive-ratchet shaft for pulling the pawllengthwise along an axis through its pivot axis for causing the printhammer to be pivoted about its axis for producing a printout, and printcontrol means for selectively pivoting the drive pawls for selectiveengagement of the pawl operating shoulders with the drive shoulder meansof the rotating driveratchet shaft for selectively actuating the printhammers for producing a printout.

2. A print hammer mechanism according to claim 1 wherein the printcontrol means comprises spring means biasing the drive pawls intoengagement with the drive-ratchet shaft and releasable latch means forreleasably holding the drive pawls against the bias of the spring meansout of engagement with the driveratchet shaft.

3. A print hammer mechanism according to claim 1 wherein the printcontrol means comprises a control shaft rotatable about an axisgenerally parallel to the axis of the drive-ratchet shaft and operablein one angular position thereof to hold the drive pawls out ofengagement with the drive-ratchet shaft and rotatable in at least oneangular direction from said one angular position thereof to release thedrive pawls for engagement with the drive-ratchet shaft for actuation ofthe hammers, a pivotal control shaft actuator pivotal in one angulardirection about an axis generally parallel to the drive-ratchet shaftaxis for rotating the control shaft in its said one angular directionfor releasing the hammer drive pawls, an actuator drive pawl having anoperating shoulder pivotally mounted on the actuator about an axisspaced from and generally parallel to the axis of the pivotal actuator,the pivotal actuator drive paw] being mounted to extend from its pivotalaxis transversely of the drive-ratchet shaft to be pivoted to bring itsoperating shoulder into engagement with the drive shoulder means of thedrive-ratchet shaft for pulling the actuator drive pawl lengthwise alongan axis through its pivot axis for pivoting the actuator in its said oneangular direction for rotating the control shaft, a pivotal control camoperable in one angular position thereof for holding the actuator drivepawl out of engagement with the drive-ratchet shaft and rotatable in atleast one angular direction for releasing the actuator drive pawl forengagement with the drive-ratchet shaft, and an electromagnetic operatoradapted upon energization for rotating the control cam in its said oneangular direction for releasing the actuator drive pawl.

4. A print hammer mechanism according to .claim 1 wherein the driveshoulder means of the elongated drive-ratchet shaft comprises a shoulderextending axially along a generally helical path and engageable with theoperating shoulders of the hammer drive pawls in succession foractuating the print hammers in succession.

5. A print hammer mechanism according to claim 1 wherein the controlmeans comprises a rotatable cam shaft extending generally parallel tothe drive-ratchet shaft and having first and second angularly spacedoperative angular positions, the cam shaft having controlling meansoperable in said first angular position of the cam shaft for camming thedrive pawls out of engagement with the drive-ratchet shaft and operablein said second angular position of the cam shaft for releasing the drivepawls for engagement with the driveratchet shaft, and cam operatingmeans for selectively rotating the cam shaft to its said second angularposition for releasing the drive pawls;

6. A print hammer mechanism according to claim 1 wherein the printcontrol means comprises first releasa-- ble latch means for holding thehammer drive pawls out of engagement with the drive-ratchet shaft, alatch actuator pivotally mounted about an axis generally parallel to thedrive-ratchet shaft axis and connected to be pivotally actuated forreleasing the first releasable latch means, an actuator drive pawlhaving an operating shoulder pivotally mounted on the latch actuatorabout an axis spaced from and generally parallel to the pivotal axis ofthe latch actuator for being pivoted to bring its operating shoulderinto engagement with the driveratchet shaft for actuation thereby foractuating the latch actuator, and second releasable latch means forholding the actuator drive pawl out of engagement with the drive-ratchetshaft.

7. A print hammer mechanism according to claim 6 wherein the camoperating means comprises a cam actuator adapted to be actuated forrotating the cam shaft to its said second angular position, an actuatordrive pawl on the cam actuator selectively engageable with thedrive-ratchet shaft for actuation thereby for actuating the camactuator, and actuator drive pawl control means for selectively engagingthe actuator drive pawl with the drive-ratchet shaft.

8. A print hammer mechanism according to claim 7 wherein the actuatordrive pawl control means comprises an electromagnetic operator operableupon energization thereof to engage the actuator drive pawl with thedrive-ratchet shaft.

9. A print hammer mechanism according to claim 8 wherein theelectromagnetic operator comprises releasable latch means for releasablyholding the actuator drive pawl out of engagement with the drive-ratchetshaft.

10. A print hammer mechanism according to claim 6 wherein the printcontrol means further comprises an electromagnetic operator connectedfor releasing the second latch means upon energization thereof.

1. A print hammer mechanism comprising an elongated rotatabledrive-ratchet shaft adapted to be continuously rotated during operationand having integral axially extending drive shoulder means, a pluralityof axially spaced hammers extending transversely of the drive-ratchetshaft and pivotally mounted about an axis generally parallel to thedrive-ratchet shaft axis to be pivotally actuated for producing aprintout, a hammer drive pawl having an operating shoulder pivotallymounted on each hammer about an axis spaced from and generally parallelto the pivotal axis of the hammer, each drive pawl being mounted toextend from its pivotal axis transversely of the drive-ratchet shaft tobe pivoted to bring its operating shoulder into engagement with thedrive shoulder means of the drive-ratchet shaft for pulling the pawllengthwise along an axis through its pivot axis for causing the printhammer to be pivoted about its axis for producing a printout, and printcontrol means for selectively pivoting the drive pawls for selectiveengagement of the pawl operating shoulders with the drive shoulder meansof the rotating drive-ratchet shaft for selectively actuating the printhammers for producing a printout.
 2. A print hammer mechanism accordingto claim 1 wherein the print control means comprises spring meansbiasing the drive pawls into engagement with the drive-ratchet shaft andreleasable latch means for releasably holding the drive pawls againstthe bias of the spring means out of engagement with the drive-ratchetshaft.
 3. A print hammer mechanism according to claim 1 wherein theprint control means comprises a control shaft rotatable about an axisgenerally parallel to the axis of the drive-ratchet shaft and operablein one angular position thereof to hold the drive pawls out ofengagement with the drive-ratchet shaft and rotatable in at least oneangular direction from said one angular position thereof to release thedrive pawls for engagement with the drive-ratchet shaft for actuation ofthe hammers, a pivotal control shaft actuator pivotal in one angulardirection about an axis generally parallel to the drive-ratchet shaftaxis for rotating the control shaft in its said one anGular directionfor releasing the hammer drive pawls, an actuator drive pawl having anoperating shoulder pivotally mounted on the actuator about an axisspaced from and generally parallel to the axis of the pivotal actuator,the pivotal actuator drive pawl being mounted to extend from its pivotalaxis transversely of the drive-ratchet shaft to be pivoted to bring itsoperating shoulder into engagement with the drive shoulder means of thedrive-ratchet shaft for pulling the actuator drive pawl lengthwise alongan axis through its pivot axis for pivoting the actuator in its said oneangular direction for rotating the control shaft, a pivotal control camoperable in one angular position thereof for holding the actuator drivepawl out of engagement with the drive-ratchet shaft and rotatable in atleast one angular direction for releasing the actuator drive pawl forengagement with the drive-ratchet shaft, and an electromagnetic operatoradapted upon energization for rotating the control cam in its said oneangular direction for releasing the actuator drive pawl.
 4. A printhammer mechanism according to claim 1 wherein the drive shoulder meansof the elongated drive-ratchet shaft comprises a shoulder extendingaxially along a generally helical path and engageable with the operatingshoulders of the hammer drive pawls in succession for actuating theprint hammers in succession.
 5. A print hammer mechanism according toclaim 1 wherein the control means comprises a rotatable cam shaftextending generally parallel to the drive-ratchet shaft and having firstand second angularly spaced operative angular positions, the cam shafthaving controlling means operable in said first angular position of thecam shaft for camming the drive pawls out of engagement with thedrive-ratchet shaft and operable in said second angular position of thecam shaft for releasing the drive pawls for engagement with thedrive-ratchet shaft, and cam operating means for selectively rotatingthe cam shaft to its said second angular position for releasing thedrive pawls.
 6. A print hammer mechanism according to claim 1 whereinthe print control means comprises first releasable latch means forholding the hammer drive pawls out of engagement with the drive-ratchetshaft, a latch actuator pivotally mounted about an axis generallyparallel to the drive-ratchet shaft axis and connected to be pivotallyactuated for releasing the first releasable latch means, an actuatordrive pawl having an operating shoulder pivotally mounted on the latchactuator about an axis spaced from and generally parallel to the pivotalaxis of the latch actuator for being pivoted to bring its operatingshoulder into engagement with the drive-ratchet shaft for actuationthereby for actuating the latch actuator, and second releasable latchmeans for holding the actuator drive pawl out of engagement with thedrive-ratchet shaft.
 7. A print hammer mechanism according to claim 6wherein the cam operating means comprises a cam actuator adapted to beactuated for rotating the cam shaft to its said second angular position,an actuator drive pawl on the cam actuator selectively engageable withthe drive-ratchet shaft for actuation thereby for actuating the camactuator, and actuator drive pawl control means for selectively engagingthe actuator drive pawl with the drive-ratchet shaft.
 8. A print hammermechanism according to claim 7 wherein the actuator drive pawl controlmeans comprises an electromagnetic operator operable upon energizationthereof to engage the actuator drive pawl with the drive-ratchet shaft.9. A print hammer mechanism according to claim 8 wherein theelectromagnetic operator comprises releasable latch means for releasablyholding the actuator drive pawl out of engagement with the drive-ratchetshaft.
 10. A print hammer mechanism according to claim 6 wherein theprint control means further comprises an electromagnetic operatorconnected for releasing the second latch means upon energizationthereof.